The traditional dry fire hydrant has two important parts. Above ground, there is an upper standpipe or barrel body with one or more outlets/nozzles projecting from the sides. At the top end of the hydrant body is a bonnet (or head or cap) having an operating nut/bolt: to use the hydrant the outlet caps (covering and protecting the outlets/nozzles) are removed so that the outlets are accessible, and the outlets are connected to one or more fire hoses, then the operating nut/bolt is turned to start the water flow.
The operating ‘nut’ connects to or is the head end of a long bar (the fire hydrant stem or fire hydrant rod) projecting straight down the length of the hydrant to the valve: thus the operating nut/bolt connects to the fire hydrant stem/rod, which runs down the interior of the standpipe/barrel and underground to the second major part of the hydrant: a main valve connected to a pressurized water main. This main valve is operated by the turning of the stem/rod: as the main valve is opened water can flood upward from the water main, through the valve, up through the underground portion of the barrel body (properly: the lower standpipe), the above ground portion (the upper standpipe) and then out via the outlets into the connected fire hoses.
Some portions may have gaskets between them.
The major problem with fire hydrants is not usually found at the bonnet end, which is easily accessible. The bonnet and operating nut and stem are secured to the standpipe body by numerous bolts through a flange. These bolts can usually be easily removed and the bonnet, nut, and other upper parts replaced if necessary, even including the upper standpipe, which may be damaged by vehicular impact or the like.
The main valve however sits underground, sometimes deep underground, with pressurized main water constantly pushing against the underside, in a location which is hard to access. Inevitably, valves sometimes corrode to the point that they no longer work and must be replaced.
The valve replacement however in itself is a major operation. Water is drained from the relevant section of the main or at least, the part of the main impacted by the defunct valve is sealed by water main isolation valves located elsewhere on the hydrant water system. The valve is threaded on the outer circumference so that it comes unseated from the threaded bushing/seat at the junction of the lower standpipe and water main, by applying torsion against a pair of projecting tabs (“ears”). However, the threads of course begin to seize up over the course of time, other parts such as the ears/tabs also begin to corrode away and inevitably it becomes hard to turn the valve to remove it from the water main.
And the tools to turn the main valve must be inserted from the top of the hydrant and then extended all the way down the upper and lower stand pipes (barrel) to the main valve to engage the ‘ears’/tabs.
Most water districts (municipalities, utilities, counties, etc) try to check their hydrants frequently. In fact, hydrants normally have an annual inspection standard, but due to the obvious cost and difficulty of valve removal, maintenance may be infrequent. Some districts report that sometimes 50% of hydrants cannot even be serviced without digging them up out of the ground entirely. To avoid having to dig the hydrant up, workers will attempt to hook construction equipment or vehicles to the upper end of the valve removal tools and thus exert enormous torsion on them despite the long vertical offset from the main valve up to the equipment pulling horizontally above ground. This in turn results in tools breaking, injuries as the jury-rigged connection from construction equipment to tool falls apart and goes flying through the air, not to mention increased costs, hydrants being unavailable when needed by fire fighters and so on.
It would be preferable to provide an effective tool for applying torsion efficiently to a hydrant main valve deep underground.
It would further be preferable to provide an efficient valve key to apply pressure to the ears of the valve.
It would further be preferable to provide an efficient means to maintain straight application of torque to a valve set deep underground.
It would yet further be preferable to provide a rescue key for use in situations in which the valve key cannot even mechanically engage the ears at all.